# FX Cross-Rate & Triangular Arbitrage API > Live cross-rate, triangular-arbitrage and conversion-path maths that FX desks and trading bots run on a set of quoted rates, computed on demand from the legs you pass in — no key, no cache, nothing stored. The cross endpoint chains two pairs that share a currency into the implied third rate (EUR/USD x USD/JPY gives EUR/JPY) and, if you supply the quoted cross, returns the discrepancy in basis points and whether it is arbitrageable. The triangular endpoint takes a closed loop of three rates and detects a triangular-arbitrage opportunity — the cycle product, the profit in percent, the winning direction (forward or reverse) and the payout on a notional. The chain endpoint converts an amount along a path of pairs and returns the amount at every hop with the effective rate. Each leg is written FROMTO:rate, meaning one unit of FROM buys that many of TO (e.g. EURUSD:1.08). This is an FX cross-rate and arbitrage engine that reasons across several pairs at once, distinct from pip/lot calculators and single-pair converters. Computed locally and deterministically, so it is instant and private. Ideal for FX arbitrage scanners, multi-currency pricing, treasury routing and trading dashboards. Live, nothing stored. 3 compute endpoints. For live quotes feed in rates from an FX or exchange API. ## Authentication All requests require your oanor API key in the `x-oanor-key` header. Get one at https://www.oanor.com/developer/keys. ```bash curl -H "x-oanor-key: oanor_live_…" "https://api.oanor.com/fxcross-api/..." ``` ## Pricing - **Free** (Free) — 4,500 calls/Mo, 2 req/s - **Starter** ($8/Mo) — 88,000 calls/Mo, 6 req/s - **Pro** ($23/Mo) — 465,000 calls/Mo, 18 req/s - **Business** ($53/Mo) — 2,850,000 calls/Mo, 45 req/s ## Endpoints ### FX #### `GET /v1/chain` — Convert an amount along a path of pairs **Parameters:** - `legs` (query, required, string) — Chained pairs FROMTO:rate Example: `EURUSD:1.08,USDJPY:150` - `amount` (query, required, string) — Amount in the first currency Example: `1000` **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/fxcross-api/v1/chain?legs=EURUSD%3A1.08%2CUSDJPY%3A150&amount=1000" ``` **Response:** ```json { "data": { "hops": [ { "pair": "EUR/USD", "rate": 1.08, "to_amount": 1080, "from_amount": 1000, "to_currency": "USD", "from_currency": "EUR" }, { "pair": "USD/JPY", "rate": 150, "to_amount": 162000, "from_amount": 1080, "to_currency": "JPY", "from_currency": "USD" } ], "path": "EUR -> USD -> JPY", "source": "FX-CROSS", "final_amount": 162000, "start_amount": 1000, "effective_rate": 162, "final_currency": "JPY", "start_currency": "EUR" }, "meta": { "timestamp": "2026-06-11T07:49:27.931Z", "request_id": "f38d62ed-930e-4e91-b297-d5a2ef15c5be" }, "status": "ok", "message": "Conversion chain computed", "success": true } ``` #### `GET /v1/cross` — Implied cross rate from chained pairs **Parameters:** - `legs` (query, required, string) — Chained pairs FROMTO:rate, comma-separated Example: `EURUSD:1.08,USDJPY:150` - `quoted` (query, optional, string) — Quoted cross to compare against Example: `163` **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/fxcross-api/v1/cross?legs=EURUSD%3A1.08%2CUSDJPY%3A150"ed=163" ``` **Response:** ```json { "data": { "base": "EUR", "legs": [ { "pair": "EUR/USD", "rate": 1.08 }, { "pair": "USD/JPY", "rate": 150 } ], "pair": "EUR/JPY", "path": "EUR -> USD -> JPY", "quote": "JPY", "source": "FX-CROSS", "arbitrage": true, "discrepancy": 1, "quoted_rate": 163, "implied_rate": 162, "inverse_rate": 0.0061728395, "discrepancy_bps": 61.73 }, "meta": { "timestamp": "2026-06-11T07:49:28.023Z", "request_id": "51be726c-6bda-439a-bb9b-556acd55f42e" }, "status": "ok", "message": "Cross rate computed", "success": true } ``` #### `GET /v1/triangular` — Triangular-arbitrage detection **Parameters:** - `legs` (query, required, string) — Closed 3-rate loop FROMTO:rate Example: `EURUSD:1.08,USDJPY:150,JPYEUR:0.00617` - `notional` (query, optional, string) — Notional to compute payout on (default 1) Example: `10000` **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/fxcross-api/v1/triangular?legs=EURUSD%3A1.08%2CUSDJPY%3A150%2CJPYEUR%3A0.00617¬ional=10000" ``` **Response:** ```json { "data": { "legs": [ { "pair": "EUR/USD", "rate": 1.08 }, { "pair": "USD/JPY", "rate": 150 }, { "pair": "JPY/EUR", "rate": 0.00617 } ], "note": "product>1 means cycling in the given (forward) direction profits; otherwise the reverse cycle does. Edge below 1 bp is treated as no arbitrage.", "source": "FX-CROSS", "notional": 10000, "arbitrage": true, "direction": "reverse", "currencies": [ "EUR", "USD", "JPY" ], "profit_pct": 0.046021, "cycle_product": 0.99954, "forward_cycle": "EUR -> USD -> JPY -> EUR", "start_currency": "EUR", "profit_on_notional": 4.60211697 }, "meta": { "timestamp": "2026-06-11T07:49:28.122Z", "request_id": "0c4b6c24-4e99-4036-a3dc-178f7567005a" }, "status": "ok", "message": "Triangular arbitrage computed", "success": true } ``` ### Meta #### `GET /v1/meta` — Spec **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/fxcross-api/v1/meta" ``` **Response:** ```json { "data": { "note": "Each leg is FROMTO:rate, where 1 FROM = rate TO (e.g. EURUSD:1.08). Legs must chain (each TO matches the next FROM).", "source": "Computed in-process from caller-supplied quoted rates (no upstream)", "service": "fxcross-api", "endpoints": { "GET /v1/meta": "This document.", "GET /v1/chain": "Convert an amount along a path of pairs, per hop (legs=EURUSD:1.08,USDJPY:150&amount=1000).", "GET /v1/cross": "Implied cross from chained pairs + discrepancy vs a quoted cross (legs=EURUSD:1.08,USDJPY:150"ed=163).", "GET /v1/triangular": "Triangular-arbitrage detection on a closed 3-rate loop (legs=EURUSD:1.08,USDJPY:150,JPYEUR:0.00617)." }, "description": "Live cross-rate, triangular-arbitrage and conversion-path maths computed on demand from the quoted rates you pass in. The cross endpoint chains two pairs sharing a currency into the implied third rate plus the discrepancy vs a quoted cross; the triangular endpoint detects a triangular-arbitrage opportunity in a closed loop of three rates (cycle product, profit %, winning direction, payout on a notional); the chain endpoint converts an amount along a path of pairs with a per-hop breakdown. An FX cross-rate and arbitrage engine that reasons across several pairs at once, distinct from pip/lot calculators and single-pair converters. Computed locally, nothing stored.", "upstream_status": "ok" }, "meta …(truncated, see openapi.json for full schema) ``` --- Marketplace page: https://www.oanor.com/api/fxcross-api OpenAPI spec: https://www.oanor.com/api/fxcross-api/openapi.json